A process for the manufacture of a 1,2-epoxide is described in the published European patent application EP 2149569. The publication describes the catalytic oxidation of an olefinically unsaturated compound using a water soluble manganese complex as the oxidation catalyst. The process described is carried out in a multiphasic system, such as a biphasic system, having an organic phase, which may be a liquid or a gaseous phase, and an aqueous phase. The actual reaction is believed to take place in the aqueous phase, and the resulting epoxide product separates from the aqueous phase into the organic phase due to low solubility of, or extraction or stripping by the organic phase. For this reason, the 1,2-epoxide is produced of a desirable turnover number (TON), with a desirable selectivity towards the 1,2-epoxide, while providing an improved ease of isolating the produced 1,2-epoxide.
While the epoxide product is recovered in the organic phase through a phase separation process, it was observed that the manganese complex is retained in the aqueous phase. Unfortunately, attempts to recover and/or recycle the manganese complex have met with limited success as the manganese complex was observed to deactivate during phase separation when the aqueous phase is not intensively mixed with the organic phase.
Therefore, there is a need for a process and apparatus for recovery or recycling of the manganese complex catalyst system.